APTampa Bay Rays' Johnny Damon (22) safely steals second base as Boston Red Sox shortstop Marco Scutaro leaps over him to grab the high throw from catcher Jarrod Saltalamacchia as umpire Dana DeMuth, left, watches during the second inning of a baseball game in St. Petersburg, Fla., Friday, Sept. 9, 2011.

ST. PETERSBURG, Fla. — The Boston Red Sox are seeing their wild card lead shrink as the injuries mount.

Wade Davis threw a six-hitter, John Jaso hit a three-run homer and the Tampa Bay Rays moved within 5 1/2 games of AL wild-card leading Boston with a 7-2 victory over the Red Sox on Friday night.

Boston has lost five of six. After two more games in Florida this weekend, the Red Sox will host Tampa Bay in a four-games series that starts Thursday at Fenway Park.

The Red Sox were without infielder Kevin Youkilis, who returned to Boston to have his sore hip examined by team doctors and undergo an MRI exam. Francona said Youkilis has bursitis and received a cortisone shot. It has not been determined if he will rejoin the team Saturday or remain in Boston until a homestand that begins Tuesday.

Boston right-hander John Lackey, Friday's starter, left with a bruised left calf after three innings. The Red Sox have not ruled out Lackey making his next start.

Davis (10-8) struck out eight in his second career complete game. The right-hander, who had his other complete game on Sept. 17, 2009, had gone 0-2 with an 11.12 ERA in three previous starts against Boston.

Jaso put the Rays ahead 3-0 with a three-run homer off Lackey (12-12) in the second.

"I'm going to keep grinding and see what happens," Lackey said. "It's not fun. There's definitely some frustration."

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Damon and Matt Joyce had RBI singles in the third to made it 5-0. Jaso later in the inning hit a two-out shot with the bases loaded off Lackey's left leg, but the pitcher recovered to picked up the ball and throw the Rays' catcher out at first.

Lackey was replaced by Scott Atchison to start the fourth. Lackey, who has lost three consecutive starts, gave up five runs, five hits and three walks in a 69-pitch outing.

Jacoby Ellsbury extended his hitting streak to 14 games with an RBI infield during a two-run sixth that got Boston within 5-2. The other run scored on Marco Scutaro's sacrifice fly.

"If you don't swing it well, don't pitch and don't play defense well, you're not going to be consistent," Boston infielder Dustin Pedroia said. "We have to find a way to win, period."

The Rays got both runs back in the bottom of the sixth on RBI doubles by Reid Brignac and Evan Longoria. Rays designated hitter Johnny Damon was back in the lineup after missing the previous three games because of a sore right leg. He had an infield single during the third that moved him past Doc Cramer into 62nd place on the all-time hits with 2,706.

Notes: It was just the seventh time in 291 career starts that Lackey went three innings or less. ... Francona said RHP's Clay Buchholz (lower back) and Josh Beckett (sprained right ankle) are making progress. A schedule for when Buchholz could throw off a bullpen mound may be determined this weekend. ... Boston recalled Atchison from Triple-A Pawtucket before the game. ... Red Sox RHP Kyle Weiland (0-1) and Tampa Bay RHP Jeremy Hellickson (12-10) are Saturday's scheduled starters.